U.S. patent application number 10/286183 was filed with the patent office on 2003-06-26 for virtual reality peripheral vision scotoma screening.
This patent application is currently assigned to The Regents of the University of California. Invention is credited to Bartsch, Dirk-Uwe G., Freeman, William R., Plummer, Daniel J..
Application Number | 20030117582 10/286183 |
Document ID | / |
Family ID | 24464509 |
Filed Date | 2003-06-26 |
United States Patent
Application |
20030117582 |
Kind Code |
A1 |
Plummer, Daniel J. ; et
al. |
June 26, 2003 |
Virtual reality peripheral vision scotoma screening
Abstract
The invention utilizes a virtual reality display to present a
random noise stimulus to a patient. Using an input device a patient
indicates the location of disturbances in the random noise display.
In a preferred embodiment, a scanning retinal laser projects the
random noise stimulus directly onto a patient's eye(s). The image
is preferably presented at virtual infinity and can be imaged over
the peripheral retina. A patient is directed to centrally fixate on
the random noise display. A visual aid, such as a cross hair, may
be included in the generated display to facilitate this focus. With
a scanning laser virtual reality device having a narrow exit, the
failure of a patient to centrally fixate causes the image presented
to be distorted, incomplete or disappear from view. While a patient
views the random noise display, the patient is directed to indicate
any areas of disturbance using an input device. A preferred input
device is a computer pen and tablet. This is easy to use while also
viewing the random noise display. Preferably, the display changes
when a patient uses the pen and tablet such that the patient sees
the location being indicated either in place of or superimposed
upon the random noise display.
Inventors: |
Plummer, Daniel J.; (San
Diego, CA) ; Bartsch, Dirk-Uwe G.; (Del Mar, CA)
; Freeman, William R.; (Del Mar, CA) |
Correspondence
Address: |
Steven P. Fallon
Suite 2500
300 South Wacker Drive
Chicago
IL
60606
US
|
Assignee: |
The Regents of the University of
California
|
Family ID: |
24464509 |
Appl. No.: |
10/286183 |
Filed: |
November 1, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10286183 |
Nov 1, 2002 |
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09615222 |
Jul 13, 2000 |
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6494578 |
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Current U.S.
Class: |
351/224 |
Current CPC
Class: |
A61B 3/024 20130101 |
Class at
Publication: |
351/224 |
International
Class: |
A61B 003/02 |
Claims
What is claimed is:
1. An entoptic perimetry vision testing apparatus comprising: a
virtual reality display; an input device; and a controller, said
controller operating to produce a random particle motion display
for display by said virtual reality display; to accept patient
input from said input device; and to store, at least, positional
data concerning the patient input.
2. The apparatus according to claim 1, wherein said virtual reality
display comprises a scanning laser retinal display device that
projects images onto a patient's eye.
3. The apparatus according to claim 2, images presented by said
scanning laser retinal display device are visible to a patient only
when the patient's vision is centrally fixated.
4. The apparatus according to claim 2, wherein said scanning laser
retinal display device presents the random particle motion display
at virtual infinity.
5. The apparatus according to claim 1, wherein said input device
comprises an electronic pad and an electronic pen.
6. The apparatus according to claim 4, wherein said controller
presents a cursor in said random motion particle display in a
orthogonal position corresponding to an orthogonal position on said
electronic pad over which said electronic pen is positioned when
said electronic pen is moved close to said electronic pad.
7. The apparatus according to claim 1, wherein said electronic pad
displays an indication at an orthogonal position where said
electronic pad is contacted by said electronic pen.
8. The apparatus according to claim 6, wherein said controller,
when said electronic pen contacts said electronic pad, suspends
said random motion particle display and displays a corresponding
indication in a corresponding orthogonal location.
9. The apparatus according to claim 1, further comprising a monitor
for displaying any image presented by the virtual reality display
device.
10. An entoptic perimetry vision testing computer program for
operating a vision test in an apparatus including a virtual reality
display and an input device, the program comprising code for:
producing a random particle motion display on the virtual reality
display; accepting patient input from the input device; and
storing, at least, positional data concerning the patient
input.
11. The program according to claim 10, wherein said producing,
accepting, and storing are repeated, and said code for storing
stores positional data concerning multiple patient inputs.
12. The program according to claim 10, further comprising code for
suspending random particle motion display when the input device is
active.
13. The program according to claim 12, further comprising code for
presenting patient input accepted by said code for accepting on the
virtual reality display while a patient is entering input to the
input device.
14. A method of diagnosing retinal scotomas, the method comprising
steps of: having a patient view a random motion particle display
presented by a virtual reality device; having the patient fixate
vision on a central part of the random motion particle display;
having the patient indicate, using an input device, any orthogonal
position in the random motion particle display having a
disturbance; noting the orthogonal position in which the patient
perceives a disturbance in the random motion particle display.
Description
FIELD OF THE INVENTION
[0001] The field of the invention is vision testing. In particular,
the invention concerns screening for peripheral scotomas.
BACKGROUND OF THE INVENTION
[0002] Evaluation of a patient's vision typically relies upon a
patient's ability to perceive normal visual stimulus. This limits
diagnosis because patients experiencing peripheral visual field
damage often remain visually asymptomatic. Patients often fail to
notice any disturbance of the visual field until damage occurs
close to the fovea. One of the most challenging problems in
ophthalmology is the development of effective retinal screening
tests for peripheral retinal disease.
[0003] Repression of pathologic blind or dark spots in a person's
visual field, i.e., scotomas, is related to the Troxler phenomenon.
In the Troxler phenomenon, a fixed spot of light above threshold
presented to the peripheral visual field will disappear from view.
This phenomenon applies primarily outside 12 degrees from fixation.
This is likely due to neural mechanisms in the brain. The
phenomenon is valuable to human vision in several respects. As an
example, the Troxler phenomenon allows eye structures in a constant
position in the visual field, e.g., blood vessels, to be repressed.
It also permits most cortical function to remain focused on a
centrally placed object of regard, except when peripheral items are
moving or changing in luminosity. However, scotomas due to retinal
injury or other pathology are also repressed by the Troxler
phenomenon, and therefore are not perceived by patients being
tested, especially if they are far from the fovea.
[0004] There are a large number of diseases which affect the
peripheral retina which current screening methods are unable to
detect with a high sensitivity (i.e., ocular melanoma, diabetic
retinopathy, CMV retinitis, branch retinal vein occlusion). Early
stages of glaucoma can exhibit such a repressed loss of peripheral
visual field sensitivity producing wedge-like defects in the
peripheral visual field. Left untreated, glaucoma often progresses
to affect the central ten degrees of vision whereby patients then
often become symptomatic. There are also diseases of the optic
nerve (e.g., optic neuritis) and primary visual cortex (e.g., AVM
producing homonymous hemianopias) which produce scotomas that are
often repressed. Early detection of all diseases first affecting
peripheral vision is accordingly essential for the prevention of
severe vision loss.
[0005] The standard diagnostic tool to diagnose peripheral scotomas
has been threshold perimetry. Entoptic, or snow-field perimetry,
has been used to detect CMV retinitis, ocular melanoma, age-related
macular degeneration, nonproliferative diabetic retinopathy, branch
retinal occlusion, and other diseases with sensitivities and
specificities over 95%. This technique uses a computer monitor
filled with random particle motion. When the monitor is viewed by a
person with normal vision, the screen appears as "visual noise".
Subjects with peripheral retinal lesions are able to outline their
scotomas. Those areas corresponding to the damaged retina appeared
to have no random motion, and are described by patients as "gray"
or "motionless" in appearance. The areas where patients perceive a
lack of random particle motion correspond to retinal lesions.
[0006] Increasing the field of vision which may be tested using
snow field perimetry requires larger computer screens and moving
the patient as close as possible to the screen. Large screens
require a large amount of space to use and store the equipment.
Moving patients closer to the screen produces a distortion of the
stimulus as people get close to the large screen (but outside the
accommodative limit) while attempting to view the image in the
peripheral retina. Patients, particularly geriatric populations who
typically suffer from many of these diseases, are unable to
accommodate well and cannot be placed close to screen to increase
the stimulus size on the visual field. Furthermore, the screens
suffer from poor contrast and a lack of lighting control. In
addition, testing suffers from refractive and accommodative error
correction.
[0007] Thus, there is a need for an improved peripheral scotoma
screening diagnostic technique, and an improved device to aid such
screening. The invention is directed to that need.
SUMMARY OF THE INVENTION
[0008] The present invention meets such a need. The invention
utilizes a virtual reality display to present a random noise
stimulus to a patient. Using an input device, a patient indicates
the location of visual field disturbances in the random noise
display. In a preferred embodiment, a scanning retinal laser
projects the random noise stimulus directly onto a patient's
eye(s). The image is preferably presented at virtual infinity and
can be imaged over the peripheral retina (outside the central 10
degrees radius, where patients are typically asymptomatic). A
patient is directed to centrally fixate on the random noise
display. A visual aid, such as a cross hair, may be included in the
generated display to facilitate this focus. With a scanning laser
virtual reality device having a narrow exit pupil, the failure of a
patient to centrally fixate causes the image presented to be
distorted, incomplete or disappear from view. While a patient views
the random noise display, the patient is directed to indicate any
areas of disturbance using an input device.
[0009] A preferred input device is a computer pen and tablet. This
is easy to use while also viewing the random noise display.
Preferably, the display changes when a patient uses the pen and
tablet such that the patient sees the location being indicated
either in place of or superimposed upon the random noise
display.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Other features, objects and advantages of the invention will
be apparent to those skilled in the art by reference to the
detailed description and the drawings, of which:
[0011] FIG. 1 is an illustration of a preferred scanning laser
entoptic perimetry vision testing device according to the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0012] Referring now to FIG. 1, shown is a vision testing device 10
constructed according to the present invention. A patient 12 is
positioned to view a stimulus through a virtual reality display 14.
A compact virtual reality display should be mounted on a suitable
adjustable stand to 15 permit viewing by patients. A random noise
stimulus is presented through the virtual reality display 14, and
the patient is able to indicate any areas of apparent disturbance
in the display using an input device 16. The device 10 may also
include a standard display monitor 18 for a practitioner to monitor
the images presented to the patient 12.
[0013] Preferably, the virtual reality display is a device to place
images on a patient's eye(s) directly. A preferred display used in
a prototype device of the invention is a retinal scanning laser
display. A prototype used a Microvision Virtual Retinal Display.TM.
system (VRD.TM.) (Microvision Inc., Seattle. Wash., USA). The
VRD.TM. projects images directly into the eye, at virtual infinity.
The VRD.TM. images over the peripheral retina. This compensates for
all but the most severe refractive errors. It also eliminates
peripheral image distortion and the quality of the image allows for
extremely high contrast. The scanning laser equipment is portable,
easily fitting within a briefcase. allowing mobility within a
clinical setting. A narrow exit pupil helps patients fixate
centrally, reducing error rates due to inappropriate fixation. A
computer tablet 20 and pen 22 are preferred for the input device
16. Such an input device is readily usable by a patient while
viewing stimulus.
[0014] A controller, in the form of software, firmware or other
code controls the virtual reality display 14 and the input device
to run the display and input. With reference now to operation of a
prototype for testing and diagnosis, artisans will recognize
preferred operational features of the device and methods for its
use. In a clinical study conducted at the Shiley Eye Center of the
University of California at San Diego, the FIG. 1 device has been
shown effective for diagnosis of peripheral scotomas.
[0015] Detection of Retinal Diseases
[0016] We recruited a total of 58 patients from the Shiley Eye
Center and from the AIDS Ocular Research Unit at the University of
California, San Diego. There was no requirement for visual acuity.
A total of 110 eyes were tested using scanning laser entoptic
perimetry. (Six patients had only one eye tested due to disease
causing complete blindness in the fellow eye). All patients were
recruited during ophthalmological visits for treatment or follow-up
of ocular disease. Participation was entirely voluntary and we
received informed consent.
[0017] Stimulus
[0018] Scanning laser entoptic perimetry consisted of a monocular
presentation on a VRD.TM. of monochromatic random particle motion.
Each "pixel value" could be either on at 635 nm or off. The VRD.TM.
delivered the entoptic stimulus through a narrow exit pupil (1 mm)
which was then viewed by the subject.
[0019] The stimulus presented to the patient through the VRD.TM.
was also "mirrored" by virtue of a video signal splitter which
displayed the identical stimulus on a computer monitor. This
allowed the experimenter to view the identical stimulus as the
patient and control the entoptic perimetry program without
interfering with the view of the patient in the VRD.TM..
[0020] Procedures
[0021] Patients were initially dilated and received their
ophthalmological examination and fundus photographs. Fundus
photographs were taken to include all areas of retinal pathology. A
diagram of lesion locations was made by a qualified
ophthalmologist. Presence and locations of these lesions was
confirmed by fundus photography, thereby effectively providing
documentation of true location of any lesions on the retina within
one hour of testing. In all cases, lesions observed by indirect
ophthalmoscopy were in complete concordance with fundus
photographs.
[0022] Next, patients were shown the computer monitor that mirrored
the stimulus inside the VRD.TM., and were shown an example of the
entoptic stimulus. Patients were given instructions on how to use
the virtual pen. Patients were explained that they would view the
identical stimulus (but for the red color) within the VRD.TM..
[0023] The entoptic program has two modes of display The stimulus
mode displays the entoptic stimulus. As the virtual pen was brought
into close proximity to a touch-sensitive pad, the stimulus mode
ended and the program entered the "recording" mode, where patients
were presented with a blank workspace for drawing. The recording
mode had several options. Placing the pen on the pad and moving it
(keeping a firm, light pressure on the stylus) produced a black
line against the background. Removing the pen from the pad but
keeping it in close proximity to the pad (i.e., closer than 1 cm)
allowed the patients to move the cursor on the screen without
drawing. Pulling the pen away from the pad further than 1 cm
returned the viewer to the stimulus mode. Placing the pen close to
the pad would again return the patient to the drawing screen, and
previously drawn scotomas would remain. In this way, participants
were able to turn the stimulus on and off under their own control.
All actions were monitored by the technician who viewed the
computer monitor during testing. This instructional phase rarely
took longer than two minutes.
[0024] After instructions, patients were then seated in front of
the VRD.TM. and asked to view the VRD.TM. with one eye (an eyepatch
was provided). They were asked to fixate in specific locations
within the visual field, and while remaining fixated, to report any
perceptual changes.
[0025] Unlike computer monitors that can be viewed from a wide
variety of angles, by virtue of the narrow exit pupil, patients had
to concentrate on fixating within the VRD.TM. in order to see the
entoptic stimulus. If their gaze wandered, the stimulus disappeared
from view and they saw a black field. Thus, unless the patient was
fixated centrally within the VRD.TM., patients were unable to see
the stimulus.
[0026] Screening to 120 Degrees
[0027] The VRD.TM. we used had a capability for screening out to 30
degrees radius when the patient was fixated centrally upon a
fixation crosshair. However, as there was no peripheral image
distortion by having the patient fixate on the corners of the
virtual screen, we placed crosshairs at the four corners of the
screen as well as halfway along the vertical and horizontal edges
of the screens. By having patients fixate on a corner of the
virtual image (e.g., lower left), we were effectively able to
screen out 60 degrees from fixation for a given quadrant. This
procedure was repeated for the three other corners in a random
order, therefore screening the entire central 120 degrees of the
retina.
[0028] Scoring Ophthalmologic Findings
[0029] Presence or absence of retinal damage was determined by an
expert ophthalmologist (WRF) using indirect ophthalmoscopy and
confirmed by fundus photography. For each of the diseases listed in
Table 1, we determined areas of damage to the retina using the
following rules:
[0030] Diabetic Retinopathy, Branch Retinal Vein Occlusion.
[0031] Areas of nonperfusion and edema as seen with fluorescein
angiography, confirmed by fundus photography. For each patient,
there were also areas which had undergone panretinal laser
photocoagulation.
[0032] CMV Retinitis.
[0033] Areas of retinal destruction by fundus photography seen as
"healed" retinitis.
[0034] Ocular Melanoma.
[0035] Areas of the retina corresponding to the location of the
tumor.
[0036] Macular Hole.
[0037] Areas relating to the hole and surrounding cuff of
fluid.
[0038] AMPPE.
[0039] Areas of the RPE disturbed despite excellent visual
acuity.
[0040] Age-related Macular Degeneration and Drusen.
[0041] Patients without laser surgery, both wet and dry, as
confirmed by fundus photography.
[0042] Retinal Detachment/Tear.
[0043] Area of retinal detachment as confirmed by fluorescein
angiography and fundus photography.
[0044] Toxoplasmosis.
[0045] Area of retinal sear as confirmed by fundus photography. The
ophthalmologist also classified lesions as within the central 10
degrees (radius) of the visual field, between 10 and 30 degrees,
from 30 to 60 degrees, or outside the central 60-degree radius, as
measured from the fovea. The ophthalmologic examination was
performed before entoptic perimetry testing.
[0046] Scoring Perimetric Findings
[0047] Presence or absence of entoptic perimetry visual field
disturbance was determined by an expert psychophysicist (DJP). If a
patient drew an area using the computer interface that corresponded
to a localized change in the entoptic stimulus, the eye was
classified as having a visual field disturbance. As with the
ophthalmologic findings, we classified visual field disturbances as
within the central 10 degrees (radius) of the visual field, between
10 and 30 degrees, from 30 to 60 degrees, or outside the central
60-degree radius, as measured from the fovea. The psychophysicist
was masked to the outcome of the ophthalmologic findings.
[0048] Statistical Analysis
[0049] For each study eye, we computed the sensitivity,
specificity, positive and negative predictive values of scanning
laser entoptic perimetry. Sensitivity was calculated as the ratio
of the number of eyes scored positive by scanning laser entoptic
perimetry to the number of eyes scored positive by fundus
photography. Specificity was calculated as the ratio of the number
of eyes scored negative by perimetry to the number of eyes scored
negative by fundus photography. Positive predictive value was
calculated as the ratio of the number of eyes scored positive by
scanning laser entoptic perimetry diagnosed as having retinal
damage to the number of eyes with entoptic disturbances. Negative
predictive value was calculated as the ratio of the number of eyes
scored negative by scanning laser entoptic perimetry diagnosed as
having retinal damage to the number of eyes without entoptic
disturbances. We calculated these summary statistics for the
following six regions: 1) lesions within the central 10 degrees
radius (perimacular area), 2) within 30 degrees (SOCA Zone 1), 3)
within 60 degrees, 4) from 10 degrees to 30 degrees, 5) from 30
degrees to 60 degrees, and 6) from 10 to 60 degrees (peripheral
retinal imaging area).
[0050] Results
[0051] A total of 58 patients (41 male, 17 female) underwent
funduscopic examination and scanning laser entoptic perimetry
testing for a total of I 10 eyes. Table I provides a breakdown of
the numbers of patients and eyes in order of the frequency of
diagnosis.
[0052] Table 2 summarizes the average (.+-.SD) sensitivity and
specificity stratified by retinal location along with both the
positive and negative predictive values stratified by retinal
location. Overall, we found that scanning laser entoptic perimetry
had sensitivities ranging from 87% to 93% and specificities ranging
from 91% to 100%, while positive predictive values range from 80%
to 100% and negative predictive values from 89% to 97%. In
particular, we found that scanning laser entoptic perimetry has a
sensitivity of 93%.+-.6%, a specificity of 100%.+-.0%, a positive
predictive value of 100%.+-.0% and a negative predictive value of
89%.+-.7% for detecting retinal lesions within the entire 120
degree visual field tested. Within the perimacular area (central 10
degrees radius of vision), where patients are usually symptomatic,
we find that scanning laser entoptic perimetry had a sensitivity of
93%.+-.9%, a specificity of 91%.+-.6%, a positive predictive value
of 80%.+-.13% and a negative predictive value of 97%.+-.5%. For
those areas where patients generally remain asymptomatic to retinal
lesions (i.e., from 10 degrees to 60 degrees radius from the
fovea), scanning laser entoptic perimetry had a sensitivity of
92%.+-.8%, a specificity of 95%.+-.5%, a positive predictive value
of 94%.+-.7% and a negative predictive value of 94%.+-.7%.
[0053] Stimulus Size and Visual Acuity
[0054] As previously reported, the optimal sensitivity for patients
with visual acuities 20/40 or better was obtained using a
high-frequency Stimulus. However, we found that patients who have
poor central visual acuity (e.g., 20/100 or less) often cannot
perceive the fine stimulus. In this study, there were a total of 8
eyes that required a larger stimulus size in order to perceive the
entoptic stimulus. For each of these cases, the patients had a poor
central visual acuity. We performed sensitivity and specificity
analyses using the minimum pixel size that the patients could
perceive.
[0055] Case Reports
[0056] The study cohort included one control patient with Behcet's
disease but no retinal damage. Despite the opacification of the
optic media, this patient was able to view the entoptic stimulus
and reported no visual disturbances to the entoptic field.
[0057] The study cohort also included a patient who presented with
a new retinal detachment (3 days). The detachment involved nearly
the entire hemifield from the far periphery nearly up to the fovea.
Upon viewing the stimulus, the patient clearly saw entoptic visual
field disturbance extending into the far periphery. The following
day the detachment was successfully repaired surgically. The
patient underwent a vitrectomy without scleral buckle, had a
long-acting gas injection and laser anterior to the equator to the
retinal breaks. No procedures that would have caused retinal
destruction occurred within the visual field. We tested the patient
one day post-operatively (two days after the initial testing
session) and despite the high refractive error introduced by the
surgical procedure (due to the gas) the patient was able to view
the entoptic stimulus (using a pixel stimulus size of 10) and found
that the entoptic disturbance had disappeared. We followed this
patient at biweekly intervals for a period of two months and found
no further visual field disturbances, and the stimulus size
required to perceive entoptic perimetry decreased with the
reduction of the refractive error due to the decrease in size of
the gas bubble. These follow-up visits were not included in the
sensitivity/specificity analyses presented above.
[0058] Detection of Glaucoma
[0059] Using procedures identical to the previous study, we
performed an experiment to determine the sensitivity and
specificity of entoptic perimetry for the detection of visual field
loss for all stages of glaucoma. As glaucoma is a disease of the
optic nerve, the "gold standard" was not fundus photography nor
fluorescein angiograms but visual field perimetry. Thus, the
scoring procedures changed as follows:
[0060] Scoring Visual Field Perimetry Findings.
[0061] Humphrey visual field printouts provide a series of measures
which evaluate visual function. For this study, we evaluated the
effectiveness of entoptic perimetry against the Humphrey Pattern
Deviation (PD) plot. The PD performs an algorithm which "corrects"
for diffuse loss due to cataracts from the total deviation (TD),
which analyzed individual visual field locations for deviations
from normal. In some cases, subjects can have a large number of
points outside of normal limits on the TD plots, but appear
relatively normal on the PD plot. In this study, we compared the
sensitivity of entoptic perimetry against PD.
[0062] Scoring was performed as follows. Using the results of
Humphrey visual field STATPAC printout, each of the 52 points
tested during the 24-2 threshold algorithm were scored as either
normal or abnormal. (The points directly above and below the blind
spot were eliminated from the analysis, reducing the number from 54
to 52.) For both pattern deviation and total deviation, each point
was classified as either normal or abnormal for four different
conditions, representing scotoma severity: 1) a point was scored as
abnormal if its sensitivity was 95% or more below of normal limits
[all scotomas] 2) if sensitivity were 98% or more below normal
limits [mild to severe scotomas] 3) if sensitivity were 99% or more
below normal limits [moderate to severe scotomas] and 4) if
sensitivity were 99.5% or more below normal limits [severe scotomas
only]. This provided us with a progressive method for comparing
entoptic perimetry tracings against visual fields with all types of
defects [all scotomas] to only those with the most severe loss of
sensitivity [severe scotomas only]. Normal limits were determined
by the Humphrey STATPAC internal database.
[0063] Clinical Assessment of Sap
[0064] An ophthalmologist experienced in the treatment of glaucoma
(AL) reviewed all Humphrey visual fields in a masked manner and
assigned one of five classifications to each visual field (Normal,
Suspect, Early, Moderate, Severe) based upon experience of
diagnosing glaucoma. Based on the ophthalmologist's five
classifications, we grouped patients into one of two groups, as
either Normal/Suspect/Early or Moderate/Severe.
[0065] Standardized Assessment of Sap
[0066] We grouped the subjects into two categories, as either
Moderate/Severe or Normal/Suspect/Early based on clinical
evaluation of the visual fields in either eye. We classified
subjects into two categories, as either Normal/Early or
Moderate/Severe based on clinical evaluation using the Ocular
Hypertension Treatment Study classification clinical evaluation of
the automated Humphrey visual fields (Table 1, (Gordon, 1995
#225]).
[0067] Results
Predictive Measures of Entoptic Perimetry vs. Sap Stratified by
Category of Clinical Assessment
[0068] Table 3 presents for each of the two categories the per-eye
and per-subject sensitivity, specificity and percent correct
classifications of entoptic perimetry for detecting
glaucoma-related visual field defects.
[0069] In general, the sensitivity of entoptic perimetry was
relatively high for subjects classified in the Moderate/Severe
group (range=0.71 to 0.90), and increased with increasingly deeper
scotomas, as reflected by greater levels of probability of
abnormalities. Specificity was 1.00 for clinical assessment. In
contrast, subjects classified as Normal/Early Suspect had low to
moderate sensitivities (range=0.27 to 0.67). Specificity was
adequate (range=0.78 to 1.00). For both sets of analyses, all
measures tended to have more predictive power (as measured by
percent correct) using the by-subject analyses and the pattern
cluster analyses.
Predictive Measures of Entoptic Perimetry vs. Sap Using the
Standardized Clinical Classification
[0070] Table 4 presents for each of the two categories the per-eye
and per-subject sensitivity, specificity, and percent correct
classifications of entoptic perimetry for detecting
glaucoma-related visual field defects. Results are similar to those
given in Table 3, namely, sensitivities and specificities are
relatively high for subjects classified in the Moderate/Severe
group, and increase with increasingly deeper scotomas, represented
by greater levels of probability of abnormalities. In contrast,
subjects classified as Normal/Early have a relatively high
specificity, but low to moderate sensitivity, despite the fact that
the overall percentage correct remains the same. As with the
Moderate/Severe group, predictive value also increases with the
more severe scotomas. For both sets of analyses, all measures tend
to have more predictive power using the by-subject analyses and the
pattern cluster analyses.
[0071] Scanning Laser Entoptic Perimetry as a General Screening
Device
[0072] This study shows that scanning laser entoptic perimetry is
sensitive and specific for screening for complete scotomas which
are the result of retinal diseases. These results demonstrate that
scanning laser entoptic perimetry is a viable possibility for a
screening test to be administered by physicians, particularly
primary care providers and in undeserved communities, where rapid,
noninvasive screening procedures can be administered by support
staff inexpensively. As entoptic perimetry screening takes less
than one minute per eye, patients could potentially be routinely
screened during annual physical checkups. This would not only allow
asymptomatic patients with potentially sight-threatening diseases
to be referred to ophthalmologists before central vision is
impacted, early detection of diseases like ocular melanoma will
allow early treatment before other organs are affected.
[0073] Analysis by Location within the Retina
[0074] In our previous studies with CMV retinitis we specifically
did not include patients with central or optic nerve damage. One of
the reasons for performing subgroup analyses within different
regions based on distance from the fovea is that only the central
portion of vision (within 10 degrees radius from the fovea) is
affected in patients with diseases like macular holes, acute
posterior multi focal placoid pigment epitheliopathy (AAVPE), and
age-related macular degeneration and these patients, usually
symptomatic, are artificially increasing our sensitivity. We
maintained a sensitivity and specificity over 90% in our subgroup
analyses which included only those areas where retinal damage would
cause patients to generally remain asymptomatic (from 10' to 60'
radius from the fovea).
[0075] This study of the present invention presents the first data
using scanning laser entoptic perimetry to screen for lesions due
to retinal disease outside the central 30' of vision. These results
show that scanning laser entoptic perimetry of the invention is as
sensitive and specific for the peripheral retina (from 30' to 60')
as we previously demonstrated for the retina out to 30'. Further,
this methodology of the invention requires no more time for
screening, unlike current standard perimetric methods such as
threshold perimetry.
ADVANTAGES OF THE INVENTION
[0076] Our previous studies demonstrated that, using a large
computer monitor, we could screen the central 30-degree radius of
vision rapidly and inexpensively. With the scanning retinal laser
used as a virtual reality display, we have now demonstrated that
scanning laser entoptic perimetry can screen for retinal disease
with a high sensitivity and specificity within the central 120
degree diameter field of vision. This is a significant improvement
over previous rapid screening methods such as the Amsler Grid,
presenting the image over 75% more retinal area. Goldmann and
Humphrey visual field perimetry can be used as screening tools for
mapping of retinal scotomas out to 180 degrees from the fovea, but
requires not only a significant investment in technicians and
overhead for the provider, but also requires considerable time from
the patient. As a result, the standard perimetric tests currently
available are not good candidates for large-scale community-based
screening programs.
[0077] Entoptic perimetry is not intended to replace the current
uses of visual field perimetry, but instead can provide a valuable
tool for the primary care provider in detecting retinal disease
early. Furthermore, the preferred virtual reality display, the
scanning retinal laser VRD.TM. is portable, and with optimization,
could become part of school-based or other screening programs. The
case reports we present also suggest that entoptic perimetry can be
used by ophthalmologists to rapidly assess visual function in
patients with opacities of the optic media which might prevent
clear views of the retina, especially in cases like cataracts or
vitritis. Furthermore, we were able to evaluate the success of
retinal detachment repair patient who was tested both pre- and
post-op. Despite the fact that the visual acuity was assessed as
hand motion, the patient was able to see the entoptic stimulus and
report that the previous visual disturbance had disappeared. Our
diabetic patient who was able to view laser bums suggests that in
screening tests, patients will be able to detect very small lesions
throughout the visual field. These results warrant further detailed
investigation.
[0078] This compensates for all but the most severe refractive
errors, and also eliminates peripheral image distortion. The
quality of the image allows for extremely high contrast. The
scanning laser equipment is portable, easily fitting within a
briefcase, allowing mobility within a clinical setting. A narrow
exit pupil in our device ensured that subjects were fixated
centrally, greatly reducing error rates due to inappropriate
fixation.
[0079] We have recently demonstrated that the FIG. 1 device with a
scanning retinal laser platform can be used to screen subjects for
damage due to infectious retinopathies out of 60 degrees radius
from the fovea. In this study, we found that scanning laser
entoptic perimetry was able to detect visual field loss due to
full-thickness retinal damage within the central 120 degrees
(diameter) of vision with a sensitivity of 92%, specificity of 95%,
positive predictive value of 94% and a negative predictive value of
94%. We present results evaluating the effectiveness of the VRD.TM.
platform for screening for glaucomatous visual field defects.
[0080] The results of the clinical testing are presented in tables
1-4 below:
1TABLE I Frequency Distribution and Diagnostic Description of Study
Eyes # companion # companion average # # patients # eyes w/ eyes
eyes sensitivity specificity lesions in average # w/diagnosis
diagnosis normal not tested central central eyes entropic Diagnosis
(n = 58) (n = 80) (n = 30) (n = 6) 120.degree. 120.degree.
w/diagnosis disturbances CMV Retinitis* 19 29 8 1 0.96 1.00 1.1 1.2
Age-related 9 14 3 1 0.86 1.00 1.0 1.0 Macular Degeneration Retinal
11 13 7 2 1.00 1.00 1.2 1.3 Detachment or Tear Diabetic 4 7 (1 with
0 1 0.71 -- 1 1 Retinopathy**** RD***) Macular Hole 4 4 4 0 1.00
1.00 1.0 1 Branch Retinal 3 3 3 0 1.00 -- 1.3 1 Vein Occlusion
Ocular Melanoma 3 3 3 0 1.00 1.00 1 1 AMPPE** 1 2 0 0 1.00 -- 1 1
Vitritis 1 2 0 0 -- 1.00 0 0 Drusen alone 2 2 1 1 1.00 1.00 1.5 2
Non-HIV Related 1 1 1 0 1.00 1.00 1 1 Toxoplasmosis *CMV =
cytomegalovirus **AMPPE = acute posterior multifocal placoid
pigment epitheliopathy ***RD = retinal detachment ****as determined
by areas of nonperfusion
[0081]
2TABLE 2 Average (.+-.SD) Sensitivity, Specificity, Positive and
Negative Predictive Values of Scanning Laser Entoptic Perimetry
Stratified by Retinal Region Positive Negative Predictive
Predictive Region Sensitivity Specificity Value Value Within
20.degree. diameter (perimacular) 93% .+-. 9% 91% .+-. 6% 80% .+-.
13% 97% .+-. 5% From 20.degree. to 60.degree. diameter 90% .+-. 11%
93% .+-. 5% 81% .+-. 14% 96% .+-. 6% From 60.degree. to 120.degree.
diameter 87% .+-. 11% 99% .+-. 2% 89% .+-. 10% 94% .+-. 8% Within
central 60.degree. diameter 90% .+-. 8% 93% .+-. 6% 92% .+-. 7% 92%
.+-. 8% Within central 120.degree. diameter 93% .+-. 6% 100% .+-.
0% 100% .+-. 0% 89% .+-. 7% Between 20.degree. to 120.degree.
diameter 92% .+-. 8% 95% .+-. 5% 94% .+-. 7% 94% .+-. 7%
(peripheral)
[0082]
3TABLE 3 Sensitivity, Specificity, and Predictive Value of Entoptic
Perimetry by Clinical Classification of Severity (number of
moderate/severe subjects/eyes = 12/21; number of
normal/early/suspect subjects/eyes = 11/20) Sensitivity Specificity
% Correct Normal/ Normal/ Normal/ Moderate/ Early/ Moderate/ Early/
Moderate/ Early/ SAP Severe Suspect Severe Suspect Severe Suspect
Pointwise Deviation by eye 95% 0.71 0.27 -- 1.00 71% 45% 98% 0.75
0.50 1.00 1.00 76% 80% 99% 0.75 0.40 1.00 0.87 76% 75% 99.5% 0.75
0.50 1.00 0.88 76% 80% Cluster Deviation by eye 95% 0.75 0.25 1.00
0.81 76% 70% 98% 0.83 0.33 1.00 0.82 86% 75% 99% 0.83 0.33 1.00
0.82 86% 75% 99.5% 0.83 0.50 1.00 0.83 86% 80% Pointwise Deviation
by subject 95% 0.75 0.38 -- 1.00 75% 55% 98% 0.82 0.60 1.00 1.00
83% 82% 99% 0.82 0.67 1.00 0.88 83% 82% 99.5% 0.82 0.67 1.00 0.88
83% 82% Cluster Deviation by subject 95% 0.82 0.50 1.00 0.78 83%
73% 98% 0.82 0.50 1.00 0.78 83% 73% 99% 0.90 0.50 1.00 0.78 83% 73%
99.5% 0.90 1.00 1.00 0.80 92% 82%
[0083]
4TABLE 4 Sensitivity, Specificity, and Negative Predictive Value of
entoptic Perimetry by Standardized Classification of Severity
(number of moderate/severe subjects/eyes = 13/23; number of
normal/early/suspect subjects/eyes = 10/18) Sensitivity Specificity
% Correct Moderate/ Normal/ Moderate/ Normal/ Moderate/ Normal/ SAP
Severe Early Severe Early/ Severe Early/ Pointwise Deviation by eye
95% 0.65 0.31 -- 1.00 65% 50% 98% 0.68 0.67 1.00 1.00 70% 89% 99%
0.67 0.75 0.50 0.93 65% 89% 99.5% 0.67 1.00 0.50 0.93 65% 94%
Cluster Deviation by eye 95% 0.67 0.67 0.50 0.87 65% 64% 98% 0.74
1.00 0.75 0.88 74% 91% 99% 0.74 1.00 0.75 0.88 74% 100% 99.5% 0.78
1.00 0.75 0.88 78% 100% Pointwise Deviation by subject 95% 0.69
0.43 -- 1.00 69% 60% 98% 0.75 0.75 1.00 1.00 77% 90% 99% 0.73 1.00
0.50 1.00 69% 100% 99.5% 0.73 1.00 0.50 1.00 69% 100% Cluster
Deviation by subject 95% 0.73 1.00 0.50 0.88 69% 90% 98% 0.80 1.00
0.67 0.88 77% 90% 99% 0.80 1.00 0.67 0.88 77% 90% 99.5% 0.89 1.00
0.75 0.88 85% 90%
[0084] While various embodiments of the present invention have been
shown and described, it should be understood that other
modifications, substitutions and alternatives are apparent to one
of ordinary skill in the art. Such modifications, substitutions and
alternatives can be made without departing from the spirit and
scope of the invention, which should be determined from the
appended claims.
[0085] Various features of the invention are set forth in the
appended claims.
* * * * *